The Muser

Physics & Physiology of Color

All the material located at this web page address is
© J. C. Adamson, and prior years,
unless otherwise noted.

Hue, Saturation & Value
The Characteristics of Color

Color is complex

We usually refer to colors by simple names such as red or blue. But of course, not all reds or blues look alike. Some are lighter or darker. Some seem richer, or more color-full. Some blues look a little greenish or purplish. So we invent other color names like mauve, chartreuse or burnt sienna, to make further distinctions between colors.

Are there more precise and descriptive ways to talk about colors? Indeed, there are many workable methods of color classification. What all these methods share though, is that they recognize three characteristics of color.

A minimum of three descriptors are always required to classify a color. For example, we can create a color from three primary colors, and simply describe the amounts of each of the three primaries used. That is the basis of describing color for web pages, and for the C.I.E. Chromaticity system used by physicists and color technicians worldwide.

But there are more descriptive, if less precise, classification methods that correspond more closely to how we perceive color. One such system was developed by A. H. Munsell between 1905 and 1929. He described colors in terms of hue, value, and chroma.

Munsell classified colors into five major hues; today we use six for most purposes. The characteristic he called chroma is approximately what we call saturation today. Munsell's system wasn't mathematically based, and failed to account for some important phenomena of color vision, but was foundational for the hue-saturation-value system (HSV or HSB) in common usage today.

Any color can be described in terms of its hue, value and saturation. A dark brown color for example, would have a hue in the yellow-red region of the color wheel. It would have a low value (because it's dark). And it would have a low saturation. A light brown color would differ from the dark brown only in its value.

Experiment in the Sandbox

Click here to play in the Color Sandbox, with hue, saturation and value.

Hue:

This color wheel shows the six major hues. There is an infinite number of hues between these colors.
 

Hue is the most obvious characteristic of a color. There is really an infinite number of possible hues. A full range of hues exists, for example, between red and yellow. In the middle of that range are all the orange hues. Similarly, there is a range of hues between any other two hues. This color wheel shows each of its six colors with medium value, and high saturation.

Saturation:
(also called chroma)

These scales show red, magenta and blue hues in a range of saturations, all with medium value.
 

Saturation is the purity of a color. High saturation colors look rich and full. Low saturation colors look dull and grayish.

Value:
(also called brightness or luminosity)

These scales shows low saturation red, magenta and blue, in a range of values.
 

Value is the lightness or darkness of a color. Light colors are sometimes called tints, and dark colors shades. All high saturation colors have medium values (because light and dark colors are achieved by mixing with white or black).

Please note: The terms chroma and saturation, and the terms value, brightness and luminosity are not exactly synonymous. All of them have precise definitions, and each is used for specific purposes in technical applications. The differences are probably not important to a basic understanding of color characteristics. In common usage for computer and design purposes they are often interchanged and used imprecisely and incorrectly.
 

© J. C. Adamson, 1997, 2012

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Additive Mixture
Subtractive Mixture
Complementary Colors
Primary Colors
Hue, Saturation, Value
Predicting Color Mixtures
Color Sandbox
Mind-Blower
Young's 3-color Theory
A 3-color System
Land's 2-color System
James Clerk Maxwell
Thomas Young
Hermann von Helmholtz
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